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AC Motor Design 1
- Thread starter bobo480
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1
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Hi bobo480
Mean length of turn may be:
Mlt=length_stator+1/2"+2*Y [Y=the width of the turn]
Y [approx]=0.8*pi*dia/no.poles
Usually 2/3 of the stator slots are used for main winding[w1] and 1/3 for auxiliary winding[w2].I think the turns ratio refers to w1/w2 ratio taking on account the winding factors as pitch shortness , fractional q[ nr of slots per pole and phase] and so on.
There is a lot of ac motor books in many languages.This one may be usefull.
FRACTIONAL AND SUBFRACTIONAL-HORSEPOWER ELECTRIC
MOTORS, by Cyril Veinott Ph.D. and by Joseph E. Martin
See Also
This is an extract[quotation] from the last:
Permanent split capacitor
A permanent split capacitor (PSC) motor, Figure 3, has neither a starting switch, nor a capacitor strictly for starting. Instead, it has a run-type capacitor permanently connected in series with the start winding. This makes the start winding an auxiliary winding once the motor reaches running speed. Because the run capacitor must be designed for continuous use, it cannot provide the starting boost of a starting capacitor. Typical starting torques of PSC motors are low, from 30 to 150% of rated load, so these motors are not for hard-to-start applications. However, unlike split-phase motors, PSC motors have low starting currents, usually less than 200% of rated load current, making them excellent for applications with high cycle rates. Breakdown torque varies depending on the design type and application, though it is typically somewhat lower than with a cap start motors.
PSC motors have several advantages. They need no starting mechanism and so can be reversed easily. Designs can be easily altered for use with speed controllers. They can also be designed for optimum efficiency and high power factor at rated load. And they're considered to be the most reliable of the single phase motors, mostly because no starting switch is needed.
Permanent split capacitor motors have a wide variety of applications depending on the design. These include fans, blowers with low starting torque needs, and intermittent cycling uses such as adjusting mechanisms, gate operators and garage door openers, many of which also need instant reversing.
Run Capacitor : These are constructed similarly to start capacitors, except for the electrolyte. They are designed to serve continuously in the run circuit of a capacitor-start /capacitor-run
Best Regards
Mean length of turn may be:
Mlt=length_stator+1/2"+2*Y [Y=the width of the turn]
Y [approx]=0.8*pi*dia/no.poles
Usually 2/3 of the stator slots are used for main winding[w1] and 1/3 for auxiliary winding[w2].I think the turns ratio refers to w1/w2 ratio taking on account the winding factors as pitch shortness , fractional q[ nr of slots per pole and phase] and so on.
There is a lot of ac motor books in many languages.This one may be usefull.
FRACTIONAL AND SUBFRACTIONAL-HORSEPOWER ELECTRIC
MOTORS, by Cyril Veinott Ph.D. and by Joseph E. Martin
See Also
This is an extract[quotation] from the last:
Permanent split capacitor
A permanent split capacitor (PSC) motor, Figure 3, has neither a starting switch, nor a capacitor strictly for starting. Instead, it has a run-type capacitor permanently connected in series with the start winding. This makes the start winding an auxiliary winding once the motor reaches running speed. Because the run capacitor must be designed for continuous use, it cannot provide the starting boost of a starting capacitor. Typical starting torques of PSC motors are low, from 30 to 150% of rated load, so these motors are not for hard-to-start applications. However, unlike split-phase motors, PSC motors have low starting currents, usually less than 200% of rated load current, making them excellent for applications with high cycle rates. Breakdown torque varies depending on the design type and application, though it is typically somewhat lower than with a cap start motors.
PSC motors have several advantages. They need no starting mechanism and so can be reversed easily. Designs can be easily altered for use with speed controllers. They can also be designed for optimum efficiency and high power factor at rated load. And they're considered to be the most reliable of the single phase motors, mostly because no starting switch is needed.
Permanent split capacitor motors have a wide variety of applications depending on the design. These include fans, blowers with low starting torque needs, and intermittent cycling uses such as adjusting mechanisms, gate operators and garage door openers, many of which also need instant reversing.
Run Capacitor : These are constructed similarly to start capacitors, except for the electrolyte. They are designed to serve continuously in the run circuit of a capacitor-start /capacitor-run
Best Regards
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